The above apparatus also is known as a minimum amount lubrication system. Such type of apparatus includes at least one oil-air mix generator producing the oil-air mix. This mixture is fed in pressurized form for purposes of lubrication to the tools of a CNC machine tool.
The nearest state of the art is a well known and previously used “minibooster system” made by the entity to which the instant application is assigned. This system comprises three oil-air mix generators each with its associated pump, which may be applied individually depending on the tool used, i.e. depending on the cross-section of the internal lubricating ducts of the particular tool.
Large diameter tools typically also exhibit large lubricating duct cross-sections, and consequently all three pumps must be operated to produce the oil-air mix in order to assure both an adequate amount of lubrication and corresponding conveyance pressure. As regards tools of smaller diameters that are fitted with commensurately smaller lubricating duct cross-sections, only one or two pumps are needed to generate an adequate film of lubrication.
It is typical practice in the state of the art to manually program the lubrication output as function of the particular tools used, namely by employing so-called M functions. M functions are standardized machine or switching commands operating a CNC machine tool. Different M functions must be used in the CNC program for each different tool. Accordingly a large number of tools must be programmed to attend to a large plurality of tools.
Programming is used to assure smooth-running production. The operation of too many pumps for a small-diameter tool and for a small cross-section of the lubrication ducts results in excessive feed pressure. Accordingly, due to this small lubrication duct cross-section, a back pressure may become so large that, in spite of sufficient lubricant in the supply receptacle, the tool nevertheless is lubricated insufficiently. In the reverse case of large tools, a similar situation arises when an insufficient number of pumps are operating.
In both instances insufficient lubricant at the tool entails increased tool wear and possibly tool failure.
Even though the previously used minibooster system has been successfully used in practice, it still leaves room for improvement because on occasion problems arise in erroneous operation, i.e. defective programming of the M-functions. In principle cutting may be fully automatic, the more so that the machines also are able to automatically change the particular tools. Therefore degradation of production on account of defective programming is considered a substantive impediment.
Accordingly embodiments of the present invention are directed to a new apparatus minimizing application of lubricants while retaining the conventional feed to tools having different and strongly diverse cross-sections of lubricant ducts, and to do so without involving elaborate, manual programming.